Method for improving development potential of an embryo and embryos developed therefrom

Abstract

The present invention relates to a method of improving development potential of an embryo, embryos developed therefrom and organisms resulting from embryos developed from the method. In a first aspect of the present invention, there is provided a method of culturing an embryo to improve development potential, said method comprising; obtaining an embryo; and culturing the embryo to enhance trophectoderm development of the embryo. The method relates to improving the chances of an embryo implanting to result in a successful pregnancy. The embryos desirably become implantation competent favouring foetal-maternal interaction and development to term of an embryo. The trophectoderm stimulating agent may be any compound which is proven to stimulate normal trophectoderm development. Preferably the agent is fibroblast growth factor-4 (FGF4) protein.

1 . A method of culturing an embryo to improve development potential, said method comprising: 
 obtaining an embryo; and    culturing the embryo to enhance trophectoderm development of the embryo.    
     
     
         2 . A method according to  claim 1  wherein the embryo is selected from the group including naturally conceived embryos, artificially fertilised embryos, nuclear transfer embryos, cloned nuclear transfer embryos or genetically modified embryos.  
     
     
         3 . A method according to  claim 1  or  2  wherein the embryo is derived from a source selected from the group including bovine, ovine, porcine, caprine, murine or human.  
     
     
         4 . A method according to any one of  claims 1  to  3  wherein the embryo is a nuclear transfer embryo.  
     
     
         5 . A method according to any one of  claims 1  to  4  wherein the trophectoderm development is enhanced by exposure of the embryo directly or indirectly to trophectoderm cells, exposure of the embryo to a trophectoderm stimulating agent, or exposure to a supernatant of a trophectoderm cell culture.  
     
     
         6 . A method according to any one of  claims 1  to  5  further including the steps of: 
 obtaining a source of trophectoderm cells; and  
 culturing the embryo in the presence of the trophectoderm cells.  
 
     
     
         7 . A method according to  claim 6  wherein the trophectoderm cells are selected from the group including mature trophectoderm cells, trophectoderm stem cells, trophectoderm vesicles or trophectoderm like cells identifiable by the expression of growth factors selected from the group including TP, FGFr-2, LIF, EGF, HB-EGF or EGFR.  
     
     
         8 . A method according to  claim 6  or  7  wherein the trophectoderm cells are cultured as a monolayer or as a cell suspension with the embryo.  
     
     
         9 . A method according to  claim 6  or  7  wherein the trophectoderm cells are aggregated with the embryo.  
     
     
         10 . A method according to  claim 9  wherein the trophectoderm cells are placed on the embryo.  
     
     
         11 . A method according to  claim 9  wherein the trophectoderm cells are cultured under the zona pellucida of the embryo.  
     
     
         12 . A method according to any one of  claims 1  to  11  wherein the embryo is developed to a morula stage.  
     
     
         13 . A method according to any one of  claims 1  to  11  wherein the embryo is developed to a blastocyst stage.  
     
     
         14 . A method according to  claim 13  wherein the trophectoderm cells are introduced into the blastocyst by injecting into the blastocyst cavity.  
     
     
         15 . A method according to  claim 14  wherein at least one trophectoderm cell is injected into the blastocyst cavity.  
     
     
         16 . A method according to any one of  claims 1  to  15  wherein the embryo is cultured to a hatching blastocyst stage.  
     
     
         17 . A method according to any one of  claims 1  to  16  wherein the embryo is cultured in the presence of a trophectoderm stimulating agent.  
     
     
         18 . A method according to  claim 17  wherein the trophectoderm stimulating agent is fibroblast growth factor-4 protein (FGF-4).  
     
     
         19 . A method according to  claim 18  wherein the FGF-4 is natural or recombinantly produced.  
     
     
         20 . A method according to any one of  claims 17  to  19  wherein the trophectoderm stimulating agent is cultured with the embryo at a stage equivalent to the morula stage of development.  
     
     
         21 . A method according to any one of  claims 17  to  20  wherein the trophectoderm stimulating agent is present at a concentration of 15 to 25 ng/ml.  
     
     
         22 . A method according to any one one of  claims 17  to  21  wherein the embryo is a genetically modified embryo which is modified to express FGF-4.  
     
     
         23 . A method according to any one of  claims 1  to  22  wherein the embryo is cultured for a period of at least 24 hours prior to transferring to a receptive animal.  
     
     
         24 . An embryo with improved development potential prepared by a method according to any one of  claims 1  to  23 .  
     
     
         25 . A method of developing an animal, said method comprising: 
 obtaining an embryo with improved development potential according to  claim 24;     obtaining a receptive animal capable of incubating an embryo to term;    implanting the embryo into the receptive animal; and    allowing the receptive animal to incubate the embryo to term.    
     
     
         26 . A method according to  claim 25  wherein the receptive animal is a female animal in a breeding cycle or is artificially induced.  
     
     
         27 . An animal prepared by the method according to  claim 25  or  26 .  
     
     
         28 . A method according to  claim 1  substantially as hereinbefore described with reference to the examples.  
     
     
         26 . An animal prepared by a method according to  claim 24 , or  25 .  
     
     
         27 . A method of determining embryo viability comprising the steps of: 
 (i) measuring expression level and/or expression timing of FGF-4; and    (ii) comparing expression level and/or expression timing to expression level and/or expression timing of an in vitro fertilised embryo, wherein embryos having similar expression levels and/or expression timing have greater viability.    
     
     
         28 . A method of screening for compounds capable of improving trophectoderm development comprising the steps of: 
 (i) obtaining an embryo    (ii) culturing said embryo, in the presence of one or more compounds suspected of improving trophectoderm development; and    (iii) comparing the ratio of inner cell mass cells to trophectoderm of the embryo from step (ii) as compared to untreated embryos.    
     
     
         29 . A compound obtained by a method according to  claim 29.